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207 Cards in this Set

  • Front
  • Back
Descriptive statistics
describe what the data shows

numeric values that help summarize a dataset to describe basic features of the data

does NOT attempt to infer a "larger truth"
Inferential Statistics
applying probability theory and math models to a set of data to reach conclusions that extend beyond the immediate data

try to reach conclusions beyond the data that you have - to 'infer" something about the general population
purposes of inferential statistics
estimation

hypothesis testing
types of descriptive statistics
measures of central tendency

measures of dispersion

describing distributions
measures of central tendency
mean

median

mode
Mean
math average

most often used - best if data are normally distributed
median
middle value in an ordered set - puth them in order from low to high and see what number is in the exact middle

often used if data is skewed - not a normal distribution (bell shaped curve)
mode
value that occurs most often in your data set - may be used when the data are normal OR skewed
types of measures of dispersion
range

variance

standard deviation
dispersion
spread of values around the central tendency - how different are the values from each other?
range
maximum - minimum

gross measurement - one single outlier can exaggerate the range
variance
sum of squares / # values - 1

take each value and subtract the mean then square the value - add all the squares together then take the number of values and subtract to find the number to divide by

this is the standard deviation squared
standard deviation
more accurate and detailed estimate of dispersion - show relation that a set of scores has to the mean in units that are meaningful

square root of the variance
standard deviation and % values
1 SD = 68% of scores
2 SD = 95% of scores
3 SD = 99% of scores
normally distributed data
then every number of central tendency will be about the same (i.e.: mean, median, and mode will all be approximately the same number)
describing distributions
shape

skewness

kurtosis
shape
symmetrical vs asymmetrical

if you fold it in half does it look the same?
modality
unimodal - 1 hump

bimodal - 2 humps

trimodal - 3 humps

easiest number to see is the mode on the graph because it will have the most occurrences
skewness
indicates the nature of asymmetrical distributions

if the data is skewed then your mean, median, and mode are not the same

if the data are skewed then the standard deviation percentages do not apply
positive skewness
the data are predominately located to the left side of the graph
negative skewness
the data are predominately located to the right side of the graph
kurtosis
the measure of how peaked or flat the distribution is

helps to describe normal distribution
leptokurtic
high kurtosis -

leaping up - very peaked

all values are very similar and close to the mean
platykurtic
low kurtosis

flat - it is flatter in data points

still with normal distribution but flatter distribution
purpose of results section
objectively present key findings from your study

uses order and logic
typically includes tables
descriptive and inferential stats
summarize results but don't interpret them until discussion
sample
just one of infinite number o possible samples from the population of interest
sampling distribution
normal distribution even if the data from each sample is NOT normally distributed
what descriptive statistic would give you the best guess at the population mean?
the sample mean

the larger the sample the better the estimate for the population mean
what descriptive statistic from the sample would allow you to know how likely your sample mean reflects your population mean?
standard deviation - tells you how much fluctuation there is -

smaller standard deviation means you are more confident that the average (mean) is correct for the population mean
standard error of the mean
theoretic value - reflects the sampling distribution

comparable to the standard deviation of raw scores except it relates to the distribution of sample means

SEM = SD/ square root of N
How do you get a small Standard Error of the Mean (SEM)
large population (N)

small standard deviation - more leptokurtic distribution of raw values
How does the standard error of the mean compare to the standard deviation?
The standard error of the mean is smaller than the standard deviation - by definition this must be true because the SEM is the SD / square root of N

The sampling distribution will be more leptokurtic than the raw data
2 purposes of inferential statistics
estimation - estimate information about the population - how confident we are in the estimation (i.e.: mean and 95% confidence)

hypothesis testing - does data support the null hypothesis? (t tests, chi square, ANOVA, correlation coefficients, regression analysis)
what is the confidence interval?
the window that the true population mean (that we cannot actually measure and we use the sampling mean to estimate it) actually falls
Inferential statistics allow the researcher to ...
1 - calculate confidence intervals regarding the "true" population mean

2 - examine the probability of a given result assuming the null is true
probability of observed values for inferential statistics
these values are compared to known distributions of the value if the null was true; this allows us to determine what the probability is of obtaining that value assuming that the null hypothesis is true (the p value)

the higher the observed statistic, the more unlikely it is that it could occur by chance factors alone
alpha
a "p" value chosen by the researcher to determine significance level

typically set to 0.05 or 0.01 at the beginning of the study - not set later but from the very beginning
statistically significant alpha
saying statistically significant means that you reject the null hypothesis thereby accepting the alternative hypothesis
alpha 0.01 vs 0.05
0.01 more stringent than 0.05 - so you would be more confident that there is an effect than just by chance if you choose 0.01

therefore making a type 1 error
statistical vs clinical significance
statistical significance - the result it real - it is unlikely due to chance or sampling error -BUT - real differences aren't necessarily important - clinical significance is a judgment call and means that the differences observed are meaningful
type 1 error
we reject the null when it is actually true and we should have accepted it -
see something but it's not really there

"convict an innocent man"
type 2 error
we retain the null (fail to reject it) when it is actually false

should have seen something that was there but you didn't

"failure to convict a guilty man"
p value
the probability of getting the value if the null is true

this is VERY IMPORTANT to researchers

how you determine if something is statistically significant
p = 0.87
this means that 87% chance that it is related to the hypothesis testing

you want a low p value to know that the null is unlikely to be true because you conduct a test to know if the alternative hypothesis is true
probability theory
helps determine whether an observed statistic would be likely if the null hypothesis was true

the larger the observed statistic the more unlikely it is that such a result would be achieved by chance if the null was true
types of T tests
one sample t test

independent t test

paired samples t test
T test
inferential statistical test used to examine whether 2 groups (defined by nominal variable) are different on some dependent variable that is measured on an interval or ratio scale

ie: Do PA and AFN students differ in their average age?

IV = program
IV levels = 2, PA or AFN
DV = average age
DV type = ratio b/c 50 is twice as old as 25
one sample t test
comparing one group to a KNOWN population mean
t test formula
t= (mean of sample) - (population mean) / standard error of the mean
how do you know if there is a large difference based on t?
t would be around zero if there is no difference and the more it differs from zero the more you have a difference
independent samples t test
comparing one group to a separate group - there is not a KNOWN population mean for comparison -

ie: do men and women CRNAs earn different starting salaries? -

the differences are not known and published - only the total mean score is published / KNOWN data
independent samples t test formula
t = (mean group 1 - mean group 2) divided by pooled estimated standard error
paired samples t test
if we are comparing same group at two different times (i.e.: midterm and final - every student takes both exams - do they score differently?)
chi square test of independence
used to analyze relationship between 2 variables when both are nominal or ordinal (or when scores have been reduced to nominal or ordinal levels because they are not normally distributed in the sample) and the two variables are measured on the same individuals
2x3 chi square analysis
there are 6 possibilities of where you might fall
if alpha = 0.01 and p = 0.011 is it significant
no - the p is more than the alpha
standard deviation - is it descriptive or inferential statistic?
descriptive
standard error of the mean - is it descriptive or inferential
inferential
what is the only value that tells you something is statistically significant?
P value
what values come from which tests?
t = T test
r = correlational test
f = ANOVA test
x = chi square test
what two test together tell you the probability that the null is true?
the p value in conjunction with the alpha value
p < or = 0.05 (assuming alpha = 0.05)
conclude that because it is SO unlikely that the null is true we will assume it isn't - reject the null and retain the alternative
bivariate linear regression
common with pearson correlation - look at the same relationship but tells you an equation to predict one variable from another variable -

you have only one independent variable predicting only one dependent variable
multiple regression
dependent variable is what you are predicting and the independent variable is the predictor -

tells you if your prediction is statistically significant - is it valid - can you use it?
p > alpha in multiple regression
tells you independent variables are not good at predicting the dependent variable

if p > alpha you reject null
one way ANOVA
comparing the means of 3 or more groups
factorial ANOVA
2 or more independent variables - how many variables there are - not how many levels of the IV
2 variables not related but want to see how they affect each other
chi square test
signal
the amount of differences between groups
noise
the amount of differences between individuals in the same group
the larger the inferential statistic the smaller the p value - is this good or bad and why
good - you hope to reject the null and accept the alternative and a small p value allows you to do so with statistical significance
how do you maximize the signal to noise ratio?

signal : noise
use well selected, reliable and valid instruments to measure construct of interest
why should you maximize N?
helps to decrease the P value and get better determination of statistical significance -

use the largest you can afford and is permitted to you
bivariate correlation
the statistical index of the degree to which two variables are associated

"pearson correlation coefficient" (r)
positive correlation coefficient
values on one variable increase the values on the other variable also increase

r = up to +1
negative correlation coefficient
values on one variable increase then the values on the other variable decrease

r = 0 to -1
strength or magnitude of correlation coefficient
numerical value between -1 and 1

closer to 1 is stronger correlation and + or - tells you if they are associated or not associated
coefficient of determination
r2 (r squared)

indicates the percent of shard variance between 2 variables

describes the over lab between variables
what is regression?
extension of correlation - specifies IV versus DV - doesn't mean that one causes the other but provides a prediction equation and can simultaneously examine more than on X as a predictor of Y - so not limited to just 2 variables
define regression
statistical technique for finding a straight line that best predicts the relationship between variables
y = b0 + b1x
equation for bivariate linear regression
what does y in bivariate linear regression equation mean?
y is the predicted value of the y axis variable = the outcome or the Dependent Variable
what does x in bivariate linear regression equation mean?
x is the x axis variable - the predictor or Independent Variable
b0 in the bivariate linear regression equation
the intercept = value of y when x = 0
what does b1 in the bivariate linear regression equation mean?
the slop of the line = the amount of change in Y for each unit change in X
what is the regression coefficient?
b1 and it provides an index of the relationship between X and Y

it is the slope!
h0: b1 = 0
there is no linear relationship between x and y
h0 : b1 not equal 0
there is a linear relationship between X and Y
what is the purpose of multiple linear regression?
the use of several IV to predict a DV
what do you need for each predictor in the multiple regression equation?
there will be a null and alternative hypothesis for each indicator in the multiple regression equation
what is the overall regression equation?
R2 (capital R squared) - proportion of variability in our outcome that can predicted by the collection of predictors in the model - it includes each unique predictors contribution as well as the overlap contribution from each predictor
what is a Factor?
the independent variable that designates the group - this is part of the ANOVA terminology

treatment condition
year of high school
ethnicity
what is a level?
individual conditions or values that make up a factor

ie: drug a, b, or c
freshman, sophomore, junior
caucasian, asian, hispanic, etc..
what is ANOVA? Why is it beneficial?
analysis of variance - a hypothesis testing procedure used to examine mean differences between multiple (3+) groups

more efficient that multiple t tests

avoids complications with finding effects that aren't really there due to use of multiple tests (decreases type 1 error rates)

provides greater flexibility in designing experiments
what does "p" represent?
the probability that differences are due to chance
what does "F" represent?
the ratio of between groups to within groups variance

signal : noise
what does if mean if F is small?
the variability between groups (signal) is negligible compared to the variation within the group (noise)

F test non significant if p > 0.05

if F is small then p will be large and therefore not significant
what does it mean if F is large?
can retain the alternative hypothesis and reject the null hypothesis -

the variability between groups is large compared to the variation within the groups (noise)

F test will be significant and p < or = 0.05
if F is significant then what?
you know that there is a difference between the means but you don't know where the differences exist - so you need to follow up with further testing to tell where the means differ

post-hoc contrasts
planned comparisons
what are effect size, relative risk, and odds ratio
additional statistical data that are increasing in use in biomedical research - in addition to the other 9 tests we've discussed
effect size
it is the magnitude of effect (a continuous measure) that accompanies (not replaces) significance testing
what is relative risk?
ratio of the incidence of an event in two different groups

incidence of a smoker developing coronary heart disease is 60% and incidence of a nonsmoker developing coronary heart disease is 20% ...the incidence f a non-smoker developing coronary heart disease is RELATIVE to the same risk for nonsmokers

therefore 60/20 = 3 the relative risk is 3 times more likely that a smoker will develop CHD than a nonsmoker
what is odds ratio?
ratio of the odds - NOT the incidences

odds of an event occurring is the probability of the event divided by the probability of the event NOT occurring
what does 1 in the odds ratio or the relative risk tell you?
indicates no difference between the groups being compared
main effect
in factorial ANOVA it is the effect of one IV on the DV
interaction effect
the combined effect of two or more IVs on the DV
standard error bars
figures that show means should show standard error bars

read the figure caption because the lines could represent the standard error the mean, the 95% confidence interval, or sometimes the standard deviation
survival curve
shows the % of the group that has NOT had the event - assume that everyone is "good' and starts at 0 together

once you fall off the curve you cannot get back on the curve -
alpha level
significant level - the specified rate that we are willing to make a type I error; set by the experimenter - conventionally it is 0.05 or less
power level
1-beta = the probability that the researcher will observe a treatment effect when it occurs - will correctly reject the null; likelihood of finding statistically significant effect when it actually exists

want this to be high - this is the chance that you are correct
effect size
measure of the strength of relationship between two variables in statistical population - in the sample we are examining
one tail
directional - the hypothesis predicts an effect in ONE direction
two tail
nondirectional - the hypothesis predicts an effect but not the direction of the effect
power
determine the sample size needed to make sure your study has the ability to reject the null if the results show the smallest "meaningful difference"
what is research?
systematic study of a problem, issue or question -

done by comprehensive literature review, search in organized way for relationships between variables, or manipulating variables to see what happens to another variable
what is the process of research?
1-establish the need for info / research
2 - research questions and hypothesis
3 - research design
4 - sampling and manipulating data collection
5 - data analysis
6 - reporting and publication
quantitative research
done to answer a specific question by reliably measuring variable and using statistical techniques to examine the outcomes

begins with a specific hypothesis to examine a specific question
what is the hourglass metaphor?
begins with broad questions (research question or theory) which then gets narrowed down (research question)
operationalize, analyze the data, reach a conclusion (results from the study) and then generalize back to the questions (conclusions of the study)
then try to get generalized back to the broad questions
qualitative research
done to generate descriptive theory grounded in the data collected - no specific research questions to tackle and the researcher is the learner

provides the foundation and guidance for quantitative research with some exceptions
what is a variable
any observation that can take different values (gender, age, race, weight, self-esteem, blood pressure)
what is an attribute
a specific value of a variable

variable = gender
attribute = male and female
what is a hypothesis?
a specific statement of prediction - must be testable
what are the two types of hypotheses
null and alternative
define a null hypothesis
describes the possible outcomes other than the one you are conducting the study to examine

usually predicts the most boring thing - there will be no effect of the IV on the DV
define the alternative hypothesis
can be directional (one tailed) or nondirectional (two tailed) - a specific prediction that usually states what you expect to happen in your study

ie: the IV will affect the DV

noted as H1 or HA
what is special about the null and alternative hypotheses?
they have no overlap but together they account for all possible outcomes and are mutually exclusive and exhaustive
what do histograms represent?
probability! - graphic depiction of data

x axis - shows all values obtained

y axis - shows the frequency at which each value occurred

when the frequency is "normally distributed" it is graphically depicted as a bell shaped curve
name 4 types of study designs
1 - true experimental
2 - quasi experimental
3 - correlational study
4 - descriptive study
what is a true experimental study?
goal is to address a specific hypothesis by demonstrating that the manipulated variable is the only possible reason for the demonstrated outcome - most detailed and stenos design

IV if the manipulated variable -
CAUSALITY - afford causal statements - IV causes DV
what 3 things are required of a true experimental study?
1 - manipulation
2 - control
3 - randomization
what is manipulation?
researcher intervention - something the experimenter does to the subject -

treatment, intervention, prevention, medication

you must manipulate to endure internal validity - you are assured that what you are doing is causing the effect
what is control?
the experimenter's ability to control or eliminate alternative explanations for changes in the DV - be assured the changes were due to manipulation in the IV
Threats to control
time
biases by the participant or the researcher
how does time threaten control of a study?
would changes in the DV occur with our without the IV? control group - a group of participants that do not undergo the active component of the IV
Treatment as usual group
how do biases affect threats to control?
systematic effect that influences the DV other than the IV - not necessarily on purpose but it happens
what are participant biases (there are 2 of them)
demand bias
expectancy effects
what is a demand bias
features of an experiment which helps participants figure out what is expected of them - it can lead them to behave in a way that would satisfy those conditions

Hawthorne effect - the effect of the participants knowledge that they are part of a study and their performance level therefore improves -

effect in the expected direction but not for the expected reason
what are expectancy effects
occurs when a subject expects a given result and therefore unconsciously reports the expected result
what is a placebo effect?
positive reports on an outcome based purely on he belief that a "treatment" will work
what is a nocebo effect?
negative effect experienced from an inert substance due to the patient's expectations (opposite of the placebo effect)

think they got an active substance and now report awful side effect when actually they did not receive the medication
what is an experimenter bias?
one that the experimenter introduces and it affects the outcome

look more closely for expected effects in the treatment group so they find them

assess outcomes differently in experimental vs control group

unconsciously communicates desire outcomes to the participant - this increases participant's demand bias - you nonverbally and unconsciously communicate the results you want them to say
how do you reduce threats to bias?
double blind, single blind, open label or randomized control trial
what is a double blind study?
both investgiator and participant are kept ignorant of the group assignment
what is a single blind study?
a study in which either the experimenter or the subject is kept ignorant of group assignment but not both
open label
both the investigator and the participant know the participant is receiving the active treatment - mostly used exclusively in biomedical research - no inactive treatment would be given to participants
what is a randomized controlled trial?
GOLD STANDARD FOR BIOMEDICAL RESEARCH
what is random assignment
method of assigning participants to the different levels of the IV, so that every subject is the sample has an equal chance of being assigned to the experimental or control group

this is to maximize likelihood that groups are equalivant prior to the administration of the IV
what is random selection
how you draw the sample of people for your study

this would not be part of the true experimental study because people have to sign informed consent and select to be in the study - this is related to sampling
what is a quasi experimental study?
design in which the conditions of true experiments are approximated

this type of experiment is used when requirements of a true experiment are not possible or are unethical
what is a correlation study?
examines the naturally occurring relationship between 2 or more variables and provides information about direction and strength of the effect - but does not provide information about causality and temporality

can have no relationship, positive or negative relationships
what are 3 types of descriptive studies?
systematic review
comprehensive systematic review
meta analysis
what is a systematic review?
look what all studies find about a particular phenomenon - figure out what the literature says about a topic - now a study design but it does employ systematic methods
what is a comprehensive systematic review?
systematic review that intends to include all studies published that meet specified criteria - you cover everything published about a topic that is in the confines that you set

ie: everything published on MS in a patient 18-35 years old with early onset - you then look for EVERYTHING published and write a paper about your findings
what is a meta analysis
application of statistical methods to combine evidence from numerous studies -

HIGHEST LEVEL OF REVIEW

you do a comprehensive systematic review then compute a statistical value or effect size which is used to measure the size of the IV on the DV for each study - this is then averaged across all studies to give a more reliable picture of the effect
what is the purpose of the methods section/
allows the reader to understand exactly how you conducted the study -

how did you get the sample?
what instrument did you use?
was the study conducted in accordance to research ethics and what analytic plan did you use?
what is the theoretical population
who you want to generalize the data back to
what is the study population
what population you can get access to
what is the sampling frame
how can you get access to the study population
what is the sample?
who is in your study
define population
scientific group from which a researcher would like to represent his / her study - the group to which the results will be able to be applied to
what is the sampling frame?
the listing of the study population from which you will draw your sample tool

ie: phone book, pt records, customer list, etc.
what is the sample
the group of people whom you select to be in your study- all who sign informed consent - some that enter the study will not be compliant and will drop out and others will be compliant the entire time and do everything right - you can't just look at those who do everything right because this would generate bias
sample bias
sample that does not represent the true population - this results in a bad sample -
what is oversampling?
a process of including a larger representation in the sample than may exist in the population - this is intentional and purposeful sampling bias - - this is a balance because you can't force people in the study and you need to try to find the population that is most representative
what is probability sampling?
any method of drawing a sample that uses some form of random selection - it helps ensure that every individual in the population has an equal chance of vein chosen to be in the sample - the data from the study has the greatest generalizability - external validity
what is simple random sampling?
most basic form of probability sampling - common methods include table of random numbers, computer random number generator, etc...

likely to misrepresent subgroups
what is non probability sampling?
does not involve random sampling - less expensive and time consuming than probability sampling - the results are limited in external validity and there is no way of knowing that the population was represented well
what is convenience sampling?
the most common type of non probability sampling - the members of the population are chased based on ease of access and the traditional per on on the street or asking for volunteers
what is ethics in research?
active pursuit of balance between the right of the scientist to search for the truth and the rich of the participant to be protected from harm
what is the nuremberg code
developed in response to nazi docs that did experiments on concentration camp inmates without consent -
included rules about informed consent, right to withdraw, justification of scientific principles and beneficence
what is the tuskegee syphillis study?
studied the effect of untreated syphillis on AA men and when PCN became the standard treatment these men were denies the standard therapy

it is now unethical to withhold a treatment that is considered the standard of care
what is the national research act?
states that all institutions sponsoring research must investigate potential risks and benefits of every study conducted both in humans and animal
what are IRB and IUCAC?
IRB - monitors clinical research on humans

IUCAC - monitors animal research
what is the belmont report
document that provides ethical framework in US on the use of humans in experimental research - reference IRB nationwide

key principles:
respect for persons
beneficence
justice
informed consent
process - not an event - required before involving them in research
3 key features of informed consent
disclose information - tells participant everything in order to make and educate

facilitate understanding - researcher available to answer any questions

promote voluntariness - person decided whether to participate or not - once they sign the consent - they can also withdraw at any time
informed consent should include
purpose
procedurs
duration
risks / discomforts
possible benefits
alternative treatments
costs
what is coercion?
over or implicit threat of harm intentionally presented by one person to another in order to obtain compliance - bad thing to motivate participation
what is undue influence?
offer of an excessive or inappropriate reward to obtain compliance - promise a good thing in order to encourage participation
what are psychometrics
the field of study concerned with the theory and technique of educational and psychological measurement -

done on instruments NOT PEOPLE
what is reliability
repeatability or consistency - gives the same result over and over

necessary but not sufficient for validity
what is test - retest reliability
assess the consistency of a result from one time to another -

participant completes the instrument and the quality being measures should not change

same person will give the same answer at different times
what is inter rater reliability?
type of scoring agreement - used to assess the degree to which different observers give consistent estimates of the same phenomenon or observation

different assessors using the same instrument will produce the same answer
what is parallel form reliability?
used to assess the consistency of the results of 2 tests constructed in the same way form the same content domain -

same person gives comparable answers on related tests delivered sequentially -

would expect that you would get similar results on test A and test B
what is internal consistency?
deriving an estimate of how well items on the instrument that reflect these same overarching theme you are trying to get at and produce similar data -

many different tools used to examine an instrument's internal consistency - CRONBACH'S ALPHA is most common
what is cronbach's alpha?
average of all split half correlations - you have computed all split half estimates of reliability - you randomly divide items into 2 sets and calculate the total score from each set for each person and obtain the correlation coefficient to reflect the relationship between the sets - similar to parallel forms reliability but with split half you do not deliver the instrument in 2 forms

0.70 considered acceptable for showing the instrument has internal consistency

0.80 is considered excellent
what are correlation coefficients?
value that ranges from -1 to +1 and tells you both about the strength of the relationship between values and the patterns of the relationship
what is validity?
accuracy
what are the 2 major types of validity?
external
internal
what is external validity?
generalizability back to situation or group you are looking at this is with sampling portion - increase external validity when you draw a non biased sample
what is internal validity?
degree to which an instrument produces accurate and true data
what is criterion related
only possible when you have another instrument in existence that is acceptable as valid - examine the accuracy of the new instrument by looking at how its scores correlated with the results from another laid instrument

measuring against the GOLD STANDARD - criterion related is determined by comparing scores to an accepted operationalization of a construct rather than to the construct itself
what is a construct
the actual quality of interest, usually difficult to measure - intelligence, knowledge, anxiety
what is operationalization
the act of translating a construct into its result - actual test or instrument that you use

i.e.:beck anxiety inventory
what is a criterion
the result of successful operationalization - the criterion variable - scores on a block exam, scores on beck anxiety inventory
what is predictive validity
test's ability to predict something it should theoretically be able to predict - an instrument is supposed to measure some future performance then predictive validity should be investigated - comparison should be made between the instrument and some later behavior or score that it predicts
what is concurrent validity
test's ability to distinguish between groups that is should theoretically be able to distinguish between - occurs when the criterion measures are obtained at the same time as the new instrument score
what is construct validity
scores of the new instrument relate appropriately to a body of criteria that define a construct - approximate truth of the conclusion that your operationalization accurately reflects its construct -

you don't have a gold standard or you have a lot of other instruments so you have a group of number you able to compare your test to
what is convergent
degree to which the test is similar to other measures that it theoretically should be similar to - so when an instrument correlates highly with other variables with which it should theoretically correlate
what is discriminant
the degree to which the test is not similar to 9diverges from) other measures that is theoretically should not be similar to - instrument does not correlate significantly with the variable from which it should differ
what are 4 levels of measurement
nominal
ordinal
interval
ratio
what is nominal data?
the number simply names the attribute uniquely - no ordering rank is applied by the numbers - so they are arbitrary and mutually exclusive
what is ordinal data?
relationship between values reflect a rank order - degree of difference between the ranks cannot be determined
what is interval data?
difference between values reflects the attribute and does have meaning - the relationship between the attributes in known and exact - averages can be computed - intervals are equal utoriginate from some arbitrary origin

no absolute zero and no negative numbers
what is ratio data?
there is an absolute and natural zero point that is meaningful
what are likert terms?
ordinal metric and commonly used in survey research - these are level of agreement assessment 5-7 point scaled used most often and are generally treated as interval level data
what is the data analytic plan
it is a decision - it discloses how the data were treated, tools investigator used and special circumstances or treatment of data that warrant justification - if included is usually a paragraph in the methods section that tells the reader how you will analyze the data - should explain and justify the investigator's decision - if strong or suspect then it helps the critical reader interpret the results and conclusion that the authors present